We are all different. Our bodies are different, our surgeons are different, there are different ways to do the surgery, etc. So the only generalization I can make is that our experiences will differ. Some like me will be an outlier on the no pain side with good ROM and some will have severe post surgery pain and ROM well below 90. Most will be somewhere in the middle.

Having said that here are my comments:

Your new knee will never feel as good as your original old one
I am only two months out and my knee feels almost as good as my real knee.

For most people it takes a full year to get most of the benefits of the surgery
That is true for many but some take longer and some get it almost immediately. I had no pain post surgery and my surgeon has me starting PT in the third week and my PT measured my ROM at 122 that week.

Many people experience a clicking sound when walking for years or forever after the surgery

You should do physical therapy for a year after the surgery to get the best range of motion results even though your therapist will discharge you after several months.
I completely agree although if you have a medicare advantage plan it might be a battle with your insurer.

There are no studies which will tell you what activities you can do after TKR. Is doubles tennis OK? Golf? What you read online varies. There are no clear answers.
That is correct. Trust your body as to what you can do post surgery. I was playing golf on the 28 day past surgery.
Many surgeons are finished with you after the surgery. If you have issues with the surgery's aftermath, they may not be that helpful.
That is terrible. My surgeon replaced my left hip about three years ago and my right knee two months ago. He has been available when I needed him but both surgeries were so successful that I didn't really need him much.

The scar is big, and no amount of ointment (vitamin E, etc.) will substantially reduce it.
My surgeon did a plastic surgery close and it is disappearing.

Good news: If you had bad knee problems before the surgery your knee will feel a lot better after the surgery.
100% agree, I was in severe pain pre surgery and now I am painless. I am 80YO male and I am back playing golf.